About a month ago, the North Oakland branch of the San Leandro-based chain Pet Food Express was hit by an armed robber. Two weeks later, it happened again, this time at the Pet Food Express Rockridge store, located in the Safeway shopping center at 51st and Broadway. According to employees, it was the same guy.

It was then that the vice president of Pet Food Express, Mark Witirol, started hearing of other armed robberies at the Rockridge shopping center. Frustrated by what he thought was a predictable pattern of crime, he wrote a letter to Mayor Ron Dellums, posting a copy on a Montclair community Yahoo group.

“For the last few months, just about every Friday night, between 5-9 p.m., one of the stores in the Safeway Center at 51st and Broadway has been robbed at gunpoint by the same person,” Witriol wrote. The letter continued: “Since the robber’s moves can be predicted, catching him should be as easy as fishing in a barrel.”

That message was then forwarded to the Rockridge Neighborhood Watch Network, magnifying its reach, as Witriol intended.

“I have raised the alarms all over the place,” he later said in a telephone interview.

The heightened attention got results. Witriol, as well as employees at various stores in the center, said they have noticed an increased police presence at the shopping center. And Witriol said that his letter prompted an outpouring of support from other Oakland residents, who wanted to know how they could help keep watch over his store and other local businesses. Perhaps most significantly, Oakland police arrested a suspect on the charges of one North Oakland robbery and are currently investigating connections into several more.

But Witriol’s original letter didn’t get it quite right. According to Oakland CrimeView, an online website affiliated with OPD that tracks recent crime trends, there have been six robberies at the Rockridge shopping center since December — a lot, but not nearly as regular a pattern as Witriol’s letter suggested. And the Oakland police said emphatically that the robberies were the work of a several robbers, not one.

Witriol’s letter may not be the most accurate portrayal of crime in North Oakland. But it spoke worlds about the city’s perception of crime, of its mood and frustrations, suspicions and cynicism. For a community beleaguered by crime, Witriol’s letter struck a chord.

“The people of Oakland are very, very upset, and they want to do something about it,” Witriol said.

The anxiety extends to those working at the shopping center, particularly at stores that have been robbed. At Jamba Juice, the site of an armed robbery this winter, most of the employees who were working at the time have since transferred to other locations. Even employees of neighboring businesses which have not been directly affected say they are nervous.

“My co-workers are very scared,” said Jocelyn Sprinkle, a Starbucks employee. Even though her store has not been robbed, she said that there was new focus on safety procedures to guard against robberies, such as bringing in outside furniture during daylight hours.

At the Dress Barn, there is now a full-time security guard sitting at the store’s entrance. An employee at GameStop, who asked not to be named because corporate headquarters has asked its employees not to speak with the media, said he was working one evening in February when a robber, armed with an automatic pistol, came into the store, demanding money from both the cash register and the store’s customers. The employee said that now he has started violating company policy of keeping doors unlocked during business hours, choosing instead to lock the doors once the sun goes down and let customers in himself.

“If it looks like one of the people that robbed me, they’re not getting in,” he said. “If they have a covering over their face, I’m not going near the door.”

But while merchants and their employees may be on the watch for a common thread, the OPD contests Witriol’s assertion that one suspect is to blame for all of the incidents.

“There is no pattern [of crime] at 51st and Broadway,” said Officer John Cunnie, a public safety officer for the nearby 12X police beat. “There is a pattern of stores getting hit, but there is no pattern in regard to one suspect.”

What is it about that particular location? Cunnie said he believes that the shopping center presents multiple opportunities for a would-be robber because there are so many stores clustered in one area.

The GameStop employee has a different theory.

“This is actually a good part of Oakland,” he said. “They [the robbers] know the security will be lax.”

The police arrested Quentin Carter earlier this month and charged him with armed robbery further down on Broadway and a parole violation. OPD Public Information Officer Jeffrey Thomason would not say whether Carter, 27, is also suspected of armed robberies at the Safeway shopping center, but he did say that police investigators are looking into possible ties to other robberies.

Witriol and other workers at the shopping center said that they believe Carter is responsible for at least some of the robbery attempts. Witriol said he believes that his employees will likely participate in a line-up to see if they can identify the suspect as the man who robbed their store.

News of the arrest has cheered many who work at the shopping center. But not all of them.

“That’s not the only guy,” the GameStop employee said. “It’s not the guy that robbed me back in February. It was the one guy that robbed us in November.”

For now, Mark Witriol is pleased with the new attention being focused on the armed robberies. When asked about the recent arrest, Witriol praised the Oakland police efforts.

“We were all amazingly impressed,” Witriol said, further adding that cooperation from Oakland residents and other business owners was crucial. “It’s not about whose job it is. When something is at this level, it’s everyone’s job.”

But although they say they hope that this arrest will result in charges for the robberies, some of the center employees remained pessimistic.

“I think it’s going to continue,” the GameStop employee said. “Not that these guys have jobs anyway, but people use the recession as an excuse to commit a crime. We’re going to continue to get robbed.”